Controls EN-ICE

Finite States Machines

An introduction

Marco Boccioli

FSM model(s) of detector control26th April 2011

The detector control system seen as pure hardware connections:

The Detector Control System

Channel 001Channel

001Channel 001Channel

009Electronics

Channel 001Channel

001Channel 001Channel

009

PCPC

Channel 001Channel

001Channel 001Channel

009

WME crate CAENSY1527

WienerPL500F8 ELMB

2

The operator usually does not know about the hardware behind a detector control system

The operator controls the detector looking at the detector topology, and not at the hardware connections

The functionalities of the equipment need to be reduced to the commonly used ones

Some command sequences can be automated

Why FSM? 3

The detector control system as the operator would like to see it:

High level of abstraction

Electronics LV

HV

LV

Temperature

Module 1

Module 2 Infra

VME

Detector

ELMB

4

Two parallel dimensions

High level of abstractionHW

Wien

erPL

500F

8

CAEN

SY15

27

Chann

el 00

1Cha

nnel

001C

hann

el 00

1Cha

nnel

009

WM

E cr

ate

Chann

el 00

1Cha

nnel

001C

hann

el 00

1Cha

nnel

009

PC

PC

ELM

BCha

nnel

001C

hann

el 00

1Cha

nnel

001C

hann

el 00

9

FSM

Elec

troni

cs

LV

HV

LVTe

mpe

ratu

re

Mod

ule

1

Mod

ule

2

Infra

VME

Detec

tor

ELM

B

5

>>

Hierarchical control of the equipments

Hierarchical control

HV LV HV LV Electronics

HV LV HV LV Electronics

Module 1

Module 2

Module 3

Power Supply

Power Supply

Detector Com

mands

Start

GoOn

SwitchOn

GoOnGoOn

Intermediate GoReady ConfigureSwitchOn SwitchOn

SwitchOnIntermediate GoReady ConfigureSwitchOn SwitchOn

6

The states are propagated up from the actual state of the devices

If needed, a sequence of commands can be automatically triggered depending on the state of the children (i.e. automatic recovery...)

Hierarchical control

Power Supply

Power Supply

Power Supply

Power Supply

Power Supply

Module 1

Module 2

Module 3

Power Supply

Detector

States

Ready

On

On

OnOn

Intermediate Ready ConfiguredOn Ready

7

Control Unit, Logical Unit Type• Modelling of behaviour for an abstract object

Device Unit Type• Modelling of behaviour based on a device type

Device Type• Software modelling of a hardware device • Usually connected via drivers

FSM units 8

CAENChannel

001

ISEGChannel

009

HV LV

Module 1

Detector

Control Unit, Logical UnitOperator

StatesCommands

Parent

StatesCommands

Child

StatesCommands

Child

StatesCommands

Child

StatesCommands

Configure, monitor and control its children

• Sequence & Automate operations

• Recover errors Handle Alarms Partition (CU only)

• Running stand-alone• Being partitioned

User Interfacing• Present information

and receive commands

• Exclusive control

CU, LU

9

Device UnitOperator

StatesCommands

Parent

StatesCommands

HW Device

ReadingsSettings

DU

Interface to the device it models

• Implement Actions• Retrieve States

Generate Alarms User Interfacing

• Present information• Receive commands• Can be excluded from

control

10

A Unit Type models the behaviour of an object• Set of COMMANDS received from the parent/operator,

translated and propagated to the children.• Set of STATES sent back to the parent/operator, according

to the state received from the children.

Finite States...

HV LV

Detector

CAENChannel

001

ISEGChannel

009

RAMPING_DOWNRAMPING_UPGO_STBY_CONF

OFF

DOWNLOADING

ONON

STBY_CONFIGUREDSTBY_CONFIGURED

GO_OFFCONFIGURE (run_mode)GO_ON

CONFIGURE(run_mode)

Type: Module

Module 1

11

Partitioning

Electronics LV

HV

LV

Temperature

Module 1

Module 2 Infra

VME

Detector

ELMB

12

An operator has exclusive control Parts of the hierarchy can be ignored

Partitioning

Electronics LV

HV

LV

Temperature

Module 1

Module 2 Infra

VME

Detector

ELMB

13

Parts of the hierarchy can be released to another operator

Partitioning

Electronics LV

HV

LV

Temperature

Module 1

Module 2 Infra

VME

Detector

ELMB

14

Parts of the hierarchy can be released to another operator

Summary The FSM is a tool for modeling devices behaviour.

• The States reflect the real hardware devices status.• The Commands are translated into settings for the devices.

FSM allows abstraction of devices• Uniform appearance also when differences in devices

behaviour. FSM allows a flexible construction of a “detector

oriented” hierarchy. It allows exclusive operation and partitioning. References:

• http://www.cern.ch/wikis/display/EN/PVSS+Service+Training+JCOP+FSM+Course• http://lhcb-online.web.cern.ch/lhcb-online/ecs/fw/FwFsm.html

15